1. Field of the Invention
The present invention relates to a portable cutting tool. A portable electric circular saw is described hereinafter as an example of the portable cutting tool.
2. Background Art
An example of a conventional portable electric circular saw is shown in FIG. 1 and FIG. 2.
As shown in FIG. 1, the portable cutting tool includes a rotating blade 1 rotationally driven by a motor (not shown), a cutting tool main body 2 to which the cutting blade 1 is attached, and a base 4 having a slide surface 3 which slides on an upper surface of a material to be cut. The cutting tool main body 2 is connected to the base 4 so as to be rotatable around a supporting shaft 5.
The cutting tool main body 2 has a motor cover 6 which covers the motor, and a gear box 7 which covers a transmitting mechanism part for reducing the rotation speed of the motor with a gear (not shown) and transmitting the rotation to the cutting blade. The motor cover 6 is connected to the gear box 7 with screws (not shown).
A saw cover 8 having a shape so as to cover the rotating blade 1 projecting at the other side of the slide surface 3 of the base 4, or the rotating blade part above the base 4, is connected to the gear box 7. A safety cover 9 having a shape so as to cover the rotating blade 1 projecting below the slide surface 3 of the base 4 is urged to the slide surface on the base 4 by a spring (not shown) to be connected to the gear box 8. Additionally, the safety cover 9 is operable by a lever 10.
A handle 12 having a switch 11 for switching on or off the motor, which is gripped by an operator during work is attached to the motor cover 6.
The handle 12 is gripped and pushed in the arrow A direction (right in FIG. 1) by an operator, thereby cutting a material to be cut advancing in the right direction in FIG. 1. Since there is a gap between the handle 12 and the rotating blade 1, it is difficult to accurately cut along the cut direction A. Therefore, cutting work is usually performed while a guide surface 14 of a guide 13 which is attached to the base 4 as shown in FIG. 3 is brought into contact with the side surface of the material to be cut.
As shown in FIG. 5, a circular saw shown in FIG. 4 is used so that work for cutting a floor material 15 located at the edge of the wall (hereinafter referred to as an edge cutting) is effectively performed. The cutting tool main body 2 is tilted in relation to the base 4 around the rotating shaft 5 so that the circular saw (hereinafter referred to as an edge cutting circular saw) can cut with the cutting blade 1 projecting outside a side end 16 of the base 4 on the opposite side of the motor.
The base 4 is rotatable in a range that the cutting tool main body 2 rotates at approximately 12° on the motor side and at approximately 45° on the opposite side of the motor around the supporting shaft 5 provided parallel to a cutting direction by the cutting tool main body 2, or parallel to an extension surface of the rotating blade 1.
A base side link, in which an arc-shaped long hole is provided around the supporting shaft 5, is provided at the front part of the base 4 in the cutting direction. Additionally, a main body side link 18, in which an arc-shaped long hole 17 is provided around the supporting shaft 5, is provided at the front part of the cutting tool main body 2 in the cutting direction. A bolt is provided as fixing means 19 capable of fixing the cutting tool main body to a desired tilted position by bringing the long hole provided in the base side link into press-contact with the long hole 17 provided in the main body side link 18 with the cutting tool main body 2 tilted in relation to the base 4 at a desired angle.
The edge cutting circular saw is formed in such a way that the width of the base 4 is reduced so that the side end 16 on the opposite side of the motor the base 4 is almost located on the extended line of the rotating blade 1. The rotating blade 1 easily projects outside the side end 16 of the base 4 and the edge cutting is easily performed by this construction.
When cutting work other than the edge cutting work is performed with the edge cutting circular saw, a sub-base 20 (see JP-A-2004-188738) for reinforcing the base 1, of which the width is reduced, shown in FIG. 6, or a dust guard 22 capable of sliding on poles 21 of the guide 13 shown in FIG. 8 and FIG. 9 and for preventing dust from jetting is attached to the edge cutting circular saw.
When the cutting work is performed with the sub-base 20 attached, as shown in FIGS. 10 to 12, the work is performed by attaching the guide 12 for accurately cutting.
The sub-base 20 and the dust guard 22 are interposition members interposing between the guide and the side end 16 on the opposite side of the motor of the base 4 in a case where a guiding part of the guide 13 is located on the opposite side of the motor, the side end 16 side where the rotating blade projects from the base.
Supporting parts 23 into which the pole 21 can be inserted are respectively provided on the front and back of the base 4 in the cutting direction in order to support the poles 21 of the guide 13, and a guide fixing bolt 25 for fixing the guide 13 movable in a direction parallel to a rotating shaft 24 of the rotating blade 1 at a desired position is provided on the supporting part 23. By changing the attachment position of the guide 13 to the base 4, the distance of the rotating blade 1 and the guide surface 14 can be adjusted.
As shown in FIG. 9, when the guide 13 is moved to the motor side with the dust guard 22 attached, the guide 13 comes into contact with an end surface on the opposite side of the motor the dust guard 22 and the movement thereof is regulated. Therefore, the guide surface 14 of the guide 13 does not come into contact with the rotating blade 1.
Additionally, FIG. 10 shows a state where the guide 13 is attached to the edge cutting circular saw, to which the sub-base 20 is attached. Since the guide surface 14 of the guide 13 is brought into slidable contact with the side surface of the material to be cut and the cutting tool is guided as shown in FIG. 11, the material to be cut can be accurately cut along a marking-off line drawn thereon.
Additionally, as shown in FIG. 12, when the guide 13 is moved to the motor side with the sub-base 20 attached to the edge cutting circular saw, the guide 13 comes into contact with an end on the opposite side of the motor of the sub-base 20 and the movement thereof is regulated. Therefore, the guide surface 14 of the guide 13 does not come into contact with the rotating blade 1.
Moreover, when the sub-base 20 is attached, a first guide 13A may be attached.